1. Technical Field
The present invention relates to a gas cell unit, an atomic oscillator, and an electronic apparatus.
2. Related Art
Generally, atomic oscillators, which oscillate based on the energy transfer of the atoms of an alkali metal such as rubidium and cesium, are broadly classified into an oscillator which uses a double resonance phenomenon due to light and microwaves (for example, see JP-A-10-284772) and an oscillator which uses a quantum interference effect (CPT: Coherent Population Trapping) due to two types of lights having different wavelengths (for example, see U.S. Pat. No. 6,806,784).
In any atomic oscillator, generally, in order to seal the alkali metal in a gas cell together with a buffer gas and keep the alkali metal in a gaseous state, there is a need to heat the gas cell to a predetermined temperature.
For example, in the atomic oscillator described in U.S. Patent Publication No. 2006-0022761, a membranous heating element formed of an ITO is provided on an outer surface of a gas cell, inside which gaseous metallic atoms are sealed, and the heating element is heated by electric conduction. As a result, it is possible to heat the gas cell and keep the metallic atoms in the gas cell in a gaseous state.
In such an atomic oscillator, generally, the electric current to be supplied to the heating element is regulated so that the temperature in the gas cell is constant. For that reason, for example, along with outdoor air temperature variations, the electric current flowing through the heating element is changed.
In this manner, when the electric current flowing through the heating element is changed, the magnetic field generated from the heating element is also changed. In the atomic oscillator of the related art, the magnetic field generated from the heating element is extensively applied into the gas cell. Thus, when the magnetic field generated from the heating element is changed, the frequency corresponding to the energy difference between the ground levels of the metallic atoms in the gas cell fluctuates. For that reason, in the atomic oscillator of the related art, there is a problem in that the output frequency deviates.